Growing shortage of crude oil supply has promoted use of other blending agents in gasoline to overcome the fuel crises worldwide. Many countries such as Brazil and US have started using more than 80% of alcohol blending in gasoline. Methanol, ethanol, t-butyl alcohols are the most promising blending agents in gasoline, ethanol being the most widely used. Alcohol blending in gasoline helps in reducing particulate emissions from the vehicle through an efficient combustion of the fuel. But such blending has its own side effects. Alcohol blending in gasoline, for example, is known to accelerate corrosion susceptibilities of metals during pipeline transportation, storage, and in car fueling systems. This is attributed to alcohol's hygroscopic nature and the impurities present in the blend. Alcohol/gasoline blends can absorb significant amounts of water (0-0.5 v/v %) without phase separation. Such moisture presence in the blended gasoline causes corrosion in metallurgy.
A variety of corrosion inhibitors have been used with the alcohol/gasoline blend to inhibit such corrosion in the metallurgy during storage, pipeline transportation, and in car fuel tank systems. These inhibitors have been disclosed to include, amongst others, aliphatic and aromatic amines, amine salts of acids such as benzoic acid, heterocyclic amine such as pyridines, alkenyl succinic acid, triazoles such as benzotriazoles and the like. Other inhibitors which have been used include metal salts such as sodium chromate, sodium silicate, ferrous nitrate, ammonium phosphate, potassium dichromate, sodium borate, quaternary ammonium salts, alkanolamines, aminophenol, alkyl and aryl mercaptans and the like.
U.S. Pat. No. 2,334,158 discloses an anti-corrosive composition of matter comprising of non-gaseous hydrocarbons containing small amounts of polycarboxylic acid having at least 16 carbon atoms and a mutual solvent for hydrocarbons and water, such as di-ethylene glycol monoether or ethylene glycol monoether.
U.S. Pat. No. 2,631,979 discloses a mineral lubricating oil containing dissolved therein 0.15 to 2% of a polymerized linoleic acid which consists essentially of the dimer of linoleic acid. U.S. Pat. Nos. 2,124,628 and 2,741,597 disclose the use of alkenyl, succinic acids as antirust agents in lubricating oils. U.S. Pat. No. 3,208,945 disclose a combination of polymerized linoleic acid and a monoalkenylsuccinic anhydride having 8 to 18 carbon atoms in the alkenyl groups as an antirust agent in the lubricating oils.
U.S. Pat. No. 3,117,091 discloses rust preventive compounds used with petroleum based carrier such as motor gasoline, aviation gasoline, jet fuel, turbine oils. These compounds are partial esters of an alkyl succinic anhydride produced by the reaction of one molar equivalent of a polyhydric alcohol with two molar equivalent of the anhydride
The corrosion inhibitors of the prior art are effective against a narrow range of metallurgies and tend to be mildly effective over a wide range of moisture content of the alcohol component of the gasohol blend. Further, the available corrosion inhibitors alter the fuel quality and property thereby compromising on the standards such as BIS & ASTM.
Therefore there is a need to develop a corrosion inhibitor which is effective against a wide variety of metallurgy and in a broad temperature and moisture range. It is also important that the corrosion inhibitor, as part of a corrosion inhibitor formulation, be completely miscible in the gasohol. Further, novel corrosion inhibitors must not alter the fuel quality and should not emulsify undesirable amount of water. Lastly, there is a need for corrosion inhibitors that do not change and/or alter any of the properties of the fuel as per specifications given by BIS & ASTM.